Conventionally, there has been known a karaoke device which automatically detects a time lag and controls a track progress state when a singer sings out of time with respect to the track progress (see Patent Document 1). With this device, karaoke accompaniment can follow the song of the singer, thereby a poor pitch singer can easily sing.
Such a time lag of content reproduction also occurs in synchronized reproduction of a DJ device. The DJ device is used for live performances which are performed by performers called as disk jockeys with turn tables or the like capable of changing pitch (speed) of tracks. Generally, performances such as DJ mix, scratch etc. are already known and floor excitement is maintained by combining special reproduction while linking tracks smoothly. Further, the synchronized reproduction is a technique by which a track as slave is reproduced in accordance with a tempo of a master track as main track.